The present invention relates to a method for applying an agrochemical mixture to a working area of a field using a vehicle moving on the field. Moreover, the invention relates to a vehicle for applying an agrochemical mixture to a working area of a field while moving on the field.
Using energy from the sun, a plant produces carbohydrates from CO2 and water. All chemical elements essential to the plant's nutrition and productivity are either mineral or non-mineral plant nutrients. The plant uses minerals to produce protein, fat, enzymes, phytohormones and vitamins. Non-mineral nutrients include carbon, hydrogen and oxygen. Plants generally consume nutrients from minerals and soil, decaying organic substances (roots, straw, humus), organic fertilizers and mineral fertilizers, airborne inputs and biological nitrogen fixation. Although arable soils may contain substantial nutrient reserves, they are usually not in plant-available form. Microorganism activity and/or chemical processes result in only a small portion of nutrients being released every year and converted into water-soluble, plant-available form. When the plant's needs cannot be met by available nutrients, fertilizers provide supplemental nutrition.
The chemical element nitrogen (N) has a special role among minerals in the soil: plants need large quantities to achieve high quality and yield. Nitrogen originates under natural conditions in the soil but in contrast to all other nutrients, it does not originate from rock but from organic compounds in the soil. Nitrogen is the fourth most common element in living tissue, after carbon, hydrogen and oxygen. An essential element in amino acids and therefore proteins, nitrogen is also a key component of chlorophyll, DNA and RNA. Without nitrogen there can be no life: no organ regeneration, and no plant development or fruit and seed formation—and ultimately no yield. This is why nitrogen is commonly referred to as the engine of plant growth.
There are two large nitrogen pools in the soil: organically bound nitrogen (95%), which is not plant-available and mineral nitrogen (5%), which is present in plant-available forms. Organic fertilizers, plant residues and the nitrogen bound by legumes (e.g., soybeans, beans, and peas) flow into the organic nitrogen pool. The mineral nitrogen pool, which consists of ammonium (NH4) and nitrate (NO3), develops from nitrogen dissolved in rain and nitrogen that enters the soil through mineral fertilizers. Ammonium and nitrate are essentially the only forms of nitrogen that plants can absorb. The organic nitrogen and the mineral nitrogen pools are in a state of constant exchange. For instance, organic nitrogen is constantly being transformed into ammonium and nitrate (a process known as mineralization), while soil organisms cause the organic fixation of mineral nitrogen (immobilization). Nitrogen depletion in the soil occurs when strong rainfall causes leaching (nitrate leaching) or when, as a result of conversion processes, gaseous combinations form that escape into the atmosphere (e.g., nitrous oxide losses).
Nitrogen losses occur as a result of organic and/or mineral fertilization and tillage. These are mainly ammonia losses and losses resulting from either nitrogen leaching or the release of nitrous oxide into the atmosphere. While nitrogen losses generally result in an economic cost for the grower, they also have a negative impact on the environment.
Ammonia losses occur mainly in livestock production, specifically during organic fertilizer storage and application (dung, manure, slurry). Significant ammonia losses also occur after the application of urea-containing fertilizers. In high concentrations, ammonia gas is toxic for humans and animals. Studies show that in 2006, increased health costs associated with ammonia emissions were an estimated 36 B US$. In addition, the pungent odor is unpleasant. Ammonia is a key component of smog; it binds with other pollutants and particles, maintaining them in air layers at or around ground level. In effect, ammonia amplifies this pollution. As a nitrogen-containing gas, ammonia can be carried great distances by the wind. Rain precipitation then often injects ammonia into natural ecosystems where it acts as a nitrogen fertilizer and has the undesired effect of boosting growth. While some plant species have a stronger reaction to nitrogen fertilization and grow better, other plants are impaired in their development. In areas where the soil has a low nutrient content, this can lead to grasses taking over and suppressing the development of rare flowering plants. In short, ammonia, has a substantially negative impact on biodiversity. Once ammonia enters the soil, it is nitrified relatively quickly, depending on temperature on some days. This goes hand in hand with soil acidification, which under extreme conditions can lead to the release of toxic heavy metals that damage plants and contaminate groundwater. Ammonia can also indirectly contribute to groundwater nitrate contamination and the formation of nitrous oxide as a result of secondary reactions.
Nitrate is water-soluble. Because negatively charged soil particles predominate in soil, the negatively charged nitrate ion—unlike the positively charged ammonium ion—will not bind to soil particles. Nitrate is therefore highly mobile in the soil and can be effectively translocated in the soil profile through diffusion and surface water movements. After heavy rainfall or low plant uptake, nitrate can leach out of the soil profile and accumulate in groundwater. In humid conditions, leached nitrates translate into a significant cost for the grower. From a toxicological perspective, threshold values have been set worldwide for groundwater levels (to avoid a transformation into nitrite in case that the water is polluted by bacteria or a transformation in the human body). Excessive nitrate concentrations are suspected of causing the following illnesses: cyanosis in newborns, stomach and intestinal cancer as a result of nitrosamine formation, and goiter. Conversely, numerous studies show that nitrate boosts the body's immune system and effectively prevents numerous diseases. Nitrate is the preferred form of nitrogen for plants, which is why nitrate in surface water bodies stimulates water plant and algae growth to the point of algal bloom. As algae and/or water plants decay, the resulting oxygen depletion (oxygen is consumed in the decomposition of organic substances from dead algae and plants) may, under extreme conditions, lead to mortality in fish populations.
Nitrous oxide (N2O) occurs during nitrification (conversion of ammonium into nitrite and nitrate through soil bacteria) as well as when nitrate exists in the soil under oxygen-poor conditions (denitrification). Next to carbon dioxide and methane, nitrous oxide is one of the most dangerous greenhouse gases. Its global warming potential is 300 times that of CO2. Nitrous oxide losses in the soil—most often only a few grams or kilograms—may represent a cost to growers as well as negative environmental impact.
The loss of nitrate and/or nitrous oxide from the soil may be reduced by a nitrification inhibitor.
One way to reduce ammonia losses is to treat urea-containing fertilizers with a urease inhibitor. A urease inhibitor effectively prevents the conversion of urea into carbamic acid and ammonia by blocking the enzyme that drives the conversion, i.e., urease. Under laboratory conditions, supplementing with urease inhibitor has been shown to prevent ammonia losses at least 70%—and in some cases 100%. The most potent known urease inhibitors include N-alkylthiophosphoric triamides and N-alkylphosphoric triamides, which are described for example in EP 0 119 487 A1.
WO 2007/093528 describes preparations with improved urease-inhibitory effect, comprising at least two different (thio)phosphoric triamides. It further describes urea-comprising fertilizers which comprise these preparations and methods for producing these preparations.
Furthermore, WO 2013/121384 describes agrochemical mixtures comprising N-n-butylthiophosphoric triamide (NBTPT) and/or N-n-propylthiophosphoric triamide (NPTPT) as a first component and at least one strobilurin as a second component in synergistically effective amounts. The application of these mixtures allows reducing ammonia and/or nitrous oxide emission from soils.
In general solid fertilizers are treated with a liquid formulation of a fertilizer additive in fertilizer plants and/or in specific application devices at fertilizer distributors and/or blenders. The ratio between fertilizer additive and fertilizer is always fixed.
One drawback of applying such agrochemical mixtures to the soil is that the ratio of fertilizer and fertilizer additive cannot be adjusted to the specific conditions, such as the soil quality and current climatic conditions.